1. Field of the Invention
The present invention relates to a vehicular automatic light control apparatus for automatically turning on and off vehicular headlights, and more particularly to a vehicular automatic light control apparatus for determining a shift from a rainfall state to a non-rainfall state and automatically controlling a headlight from a turned-on state to a turned-off state.
2. Description of the Related Art
Heretofore, there has been known a method of and an apparatus for automatically operating vehicular headlights by measuring a period of time in which a windshield wiper has operated and the number of cycles in which the windshield wiper has wiped the windshield in each of intermittent, low-speed, and high-speed modes of operation of the windshield wiper, and judging a rainfall when the period of time and the number of cycles have reached respective values. See, for example, Japanese Laid-Open Patent Publication No. 2000-168435.
The applicant has proposed a rainfall determining device for judging a rainfall based on information as to the wiping operation of a windshield wiper. According to the proposed rainfall determining device, a wiping operation detecting means detects each wiping operation of the windshield wiper, and a timer starts measuring a predetermined period of time in each detected wiping operation. A counter counts the number of cycles in the predetermined period of time in which the windshield wiper has wiped the windshield, and if the count is detected successively a predetermined number of times, then a judging means judges a rainfall. For details, reference should be made to Japanese Patent Application No. 2004-103519.
The conventional arrangement disclosed in Japanese Laid-Open Patent Publication No. 2000-168435 requires a dedicated timer and a dedicated counter for each of the operation modes of the windshield wiper, the timer and the counter being controlled under different conditions in the respective modes. The disclosed apparatus for judging a rainfall is complex in structure. The disclosed method and apparatus turn on the headlights when a rainfall is judged depending on the operation mode of the windshield wiper, and do not judge a non-rainfall state.
The proposal according to Japanese Patent Application No. 2004-103519 also judges a rainfall and does not judge a non-rainfall state.
As described above, there has not been any conventional non-rainfall judging apparatus for determining a shift from a rainfall state to a non-rainfall state.